On the calculation of energy release rate in composites by Finite Elements, Boundary Elements and Analytical Methods

To characterize a transversal crack evolution in a cross-ply [0/90]s fiber reinforced composite laminate, the associated energy release rate (ERR) was calculated by means of the J-integral embedded into the finite element method (FEM). The ERR values computed for the propagation of the transversal crack were correlated to the ones obtained by using the virtual crack closure technique (VCCT) embedded within the boundary element method (BEM). In addition, the results were compared with analytical values. The results correlated well except when the crack length was approximately 80% of the ply thickness. In such case, ERR values showed some discrepancies between FEM and BEM. The reason stems from the fact that in the VCCT used not all components of the stresses are considered, resulting in smaller ERR values. In addition, the results proved that transversal cracks can influence each other only at a limited distance.